SANAA, Yemen — Pro-government fighters in Yemen have received weapons shipments in the war-torn city of Aden, as Shiite rebels scramble to deploy reinforcements, military officials from both sides said Sunday.

Military and port officials in Aden said new heavy and medium weapons and ammunition arrived there late last month by sea to support pro-government army divisions and militias against the Shiite Houthi rebels and allied military units.

The officials said tanks, artillery, missiles and armored vehicles were included in the shipment from Saudi Arabia and the United Arab Emirates, which have been waging a U.S.-backed air campaign against the Iran-supported rebels since March.

After months of fierce fighting, pro-government forces recently pushed rebels out of Aden and advanced in Taiz, Yemen's third-largest city.

The fighting in Yemen pits the Houthis and troops loyal to former President Ali Abdullah Saleh against southern separatists, local and tribal militias, Sunni Islamic militants and loyalists of exiled President Abed Rabbo Mansour Hadi, who is now in Saudi Arabia.

He urged his fighters to stand their ground, saying "you are leading a battle of honor and glory and freedom, and holy defense which is legitimate."

Al-Houthi said the "aggressor" sought to humiliate Yemenis and called exiled Hadi's legitimacy "meaningless."

Military officials close to the Houthis in the rebel-held capital Sanaa said the rebels are continuously sending military reinforcements south to Aden and Taiz, suggesting major losses.

They said the Houthis are determined to continue fighting in Aden and Taiz, and have demanded that allied tribes send fighters to the two fronts. The Houthis are also actively recruiting new fighters in mosques, the officials said.

Security officials and witnesses said Sunday that pro-government forces, reinforced with tanks and rockets, are waging a heated battle at the Houthi outpost of al-Khadra, north of Aden. The sound of clashes and shelling can be heard for miles around, they said. Residents in nearby Dar Saad said smoke and flames are rising from the battle area.

Military officials said their forces advanced under air cover after removing mines placed by the rebels.

All officials spoke on condition of anonymity because they were not authorized to speak to journalists.

Saudi Arabia said one of its citizens was killed Sunday when a house inside the kingdom was struck by fire from neighboring Yemen.

A civil defense spokesman, Ali bin Omair al-Shahrani, said in comments to the official Saudi Press Agency that the Saudi was killed in the border town of Najran.